Spark-plug tester



Heb. 26 1924.

B. C. DOPPES ET AL SPARK PLUG TESTER Filed .March 21. 1921 0 z 2 v fi "UH I A a 4 a 9 z Patented Feb. 26, 1924.

UNITED STATES PATENT emu.)

BERNARD C. DOPPES AND HARRY W. CENTNER, OF CINCINNATI OHIO.

SPARK-PLUG TESTER.

Application filed March 21, 1921. Serial No. 454,176.

To all whom it may concern.

Be ltjknown that we, BERNARD C.Dorrns and HARRY W. CENTNER, both of uscitizens of'the United States of America, and residing'at Cincinnati, inthe county of Hamilton and State of Ohio, have jointly invented acertain new and usefullmprovementf in Spark-Plug Testers, of which thefollowing is a specification;

This invention relates to testing'implements for use in connection withsparkplugs for internal-combustion engines; and its object is to providea convenient handtool that has a spark space or gap in its structurethat responds to a short circuit through the tool itself when applied tothe spark-plugs and in plainly visible sight of those havingautomobiles, gas-engines, motor-cycles, aeroplanes, motor-boats,farmtractors in their use, or those having public garage service andothers employing electric ignition in the operation of the said class ofmachines.

A special object of the invention is to produce a device of saidcharacter that shall be simple and durable in construction, inexpensiveand easy to manufacture, and which will always be efiicient and reliablein its testing application.

The invention consists of the novel features of construction,combination and arrangement of parts which will be hereinafter referredto and more particularly pointed out in the description and claim.

In the accompanying sheet of drawings, Figure 1 is a perspective viewshowing our invention herein complete and in position for application;Fig. 2, a central, longitudinal section; and Fig. 3, a longitudinalelevation showing the testing device in using position at the upper endof a spark-plug.

4: indicates a suitable wooden handle having a narrow longitudinal kerfor slit 5 that extends about half its length;

6 indicates a flat strip of insulating material whose inner end istightly clamped within the said kerf 5 of the handle by means of a'pairof screws 7, 7. Strip 6 extends outwardly a suitable distance from thehandle to receive and hold at its outer end a flat metal strip or plate8 that is duly secured by means of a rivet 9. An aperture 10 is piercedin the outer end of the strip 8 to facilitate its proper engagement withthe plug for ignltion service.

upper extension stem' 11 of the spark-plug 12, the-latter being of anyordinary or ap proved type and mounted on the engine 13,

a small fragment only of the latter being 7 shown. 1

The inner end of the metal strip or 7 point or tip 1 1;, as best shown 8tapers to 'a in Fig. 1.

1-5. is a short metal strip or narrow plate 7 mounted on theuppersurface of the. said insulating strip 6, to-the rear of the saidmetal strip or plate 8, being duly secured" in place by means of a rivet16 and having a vertical leg member 17 extending downwardly, at a rightangle, through a transverse slot 18 that is made in'the said insulatingstrip 6 a slight distance forward of the fore end of the handle 4:. Thefore end of the short metal strip or plate 15 tapers to a point or tip18 similar to the tip 14 at the inner end of the metal strip 8 and isduly spaced therefrom to produce the required gap for testingthe sparkinthe plug 12 in the desired operation of the engine."

In such testing operation, if no ignition current is present on accountof any defects ora lack of battery, the absence of a spark in the gapwill of coursebe immediately dis-I closed, while, on the other hand, thevisible spark in the said gap will instantly indicate or disclose normalworking conditions of the ignition current. The upper end of the metalleg member 17 is secured by means of a rivet 19 to the outer face of abroad transverse guard plate 20 that is made of insulating material andprovided with a horizontal slot 21 through which the first;

named insulating strip 6 passes from the f handle at, the inner faceofsa d guard plat-o being arranged to lie in contact with the end of thesaid handle from which the said in sulating strip 6 projects. The saidguard strip is intended for use in protecting the hand from contact withthe current when using'the implement herein in testing the The extremelower end of the metal leg member 17 of the spark indicating strip 15extends to and in contact with the upper part of the engine 13 forgrounding through the latter in of fecting or closing circuit of thecurrent across the spark gap between the points 14 and 18. The twonarrow metal strips or "plates 8 and 15 are short ones so that the paththerethrough shall be more direct and the spark more positively effectedin the said gap for the testing service.

It is obvious that instead of providing the aperture 10 in the outer endof the metal strip 8 the metal can be struck up into a flange orprotuberance, thereby leaving a socket or stop on the underside of thestrip 8 for the ready placement or setting on the top stem 11 of thespark-plug, but the setting or placing of the tool in testing positionwould not be as positive or as-free from slipping or shifting sidewise.Besides, the said aperture affords a convenient means of hanging thetool on a hook or nail handy to the user.

We claim In a hand testing implement for sparkplugs of electric ignitioninternal-combustion engines, the combination of a-suitable handle, aninsulating strip extending longitudinally from one end of said handle,an

insulating guard plate having a transverse slot through which saidinsulating strip on the handle extends outwardly, a short narrow metalstrip extending from the outer end of the said insulating strip andhaving a pointed inner end, and a narrow metal strip mounted on theupper surface of said insulating strip immediately forward of said guardplate but to the rear of the pointed inner end of'the said short metalstrip andialso having a pointed outer end that corresponds to that atthe adjacent but spaced pointed inner end of the first-named metal stripto produce the desired detecting or testing spark gap, and apendentintegral metal strip extending through a transverse slot madein the saidinsulating strip at a right angle from the inner end of the saidrear'metal plate on the said insulating strip to a point below the loweredge ofsaid insulating guard plate for grounding a short circuit throughthe engine and producing-a spark in the said gap when ignition currentis normally intact in the spark-plug, substantially as herein shown anddescribed.

BERNARD C. DOPPES. HARRY W. CENTNER.

